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| United States Patent |
5,632,614
|
|
Consadori
, et al.
|
May 27, 1997
|
Gas fired appliance igntion and combustion monitoring system
Abstract
A gas fired appliance measures infrared emissions from a metal object
heated in a combustion chamber to evaluate combustion. Associated
circuitry uses the evaluation to control operational parameters of the
appliance, including fuel and air fed to the appliance. A second metal
object, prior to fuel ignition, is electrically heated to emit infrared
radiation. Infrared emissions from the second metal object, indicative of
the temperature thereof, are monitored to assure an ignition temperature
to ignite a combustible air and fuel mixture. A fan directs a stream of
ambient air upon the second metal object to cool the same and reduce the
infrared emanating therefrom. The reduction in infrared from the second
metal object is monitored to verify proper fan operation.
| Inventors:
|
Consadori; Franco (Salt Lake City, UT);
Field; D. George (Pleasant Grove, UT);
Banta; Kevin D. (Sandy, UT);
Nichols; Gary S. (Sandy, UT)
|
| Assignee:
|
Atwood Industries , Inc. (Rockford, IL)
|
| Appl. No.:
|
499420 |
| Filed:
|
July 7, 1995 |
| Current U.S. Class: |
431/79; 219/260; 431/63; 431/66; 431/74 |
| Intern'l Class: |
F23N 005/08 |
| Field of Search: |
431/79,74,62,63,66
|
References Cited
U.S. Patent Documents
| 2840146 | Jun., 1958 | Ray | 431/79.
|
| 3902841 | Sep., 1975 | Horn | 431/79.
|
| 3903418 | Sep., 1975 | Horn | 250/338.
|
| 3975137 | Aug., 1976 | Hapgood | 431/78.
|
| 4435149 | Mar., 1984 | Astheimer | 431/12.
|
| 4505668 | Mar., 1985 | DiBiano et al. | 431/202.
|
| 4595353 | Jun., 1986 | de Haan | 431/263.
|
| 4778378 | Oct., 1988 | Dolnick et al. | 431/79.
|
| 4878831 | Nov., 1989 | Ewing | 431/79.
|
| 4898531 | Feb., 1990 | Goldstein et al. | 431/79.
|
| 4927350 | May., 1990 | Zabielski | 431/12.
|
| 4976608 | Dec., 1990 | Hyde | 431/202.
|
| 5052661 | Oct., 1991 | Dunlay et al. | 266/87.
|
| 5111048 | May., 1992 | Devitt et al. | 250/342.
|
| 5112217 | May., 1992 | Ripka et al. | 431/12.
|
| 5245196 | Sep., 1993 | Cabalfin | 250/554.
|
| 5281243 | Jan., 1994 | Leininger | 44/629.
|
| 5322216 | Jun., 1994 | Wolter et al. | 236/25.
|
| 5332386 | Jul., 1994 | Hosome et al. | 431/12.
|
Primary Examiner: Dority; Carroll B.
Attorney, Agent or Firm: Workman, Nydegger & Seeley
Claims
What is claimed and desired to be secured by United States Patent is:
1. An appliance fired by a combustible gas mixture producing combustion
flames upon ignition, and comprising:
means for supplying said combustible gas mixture;
hot surface ignition means, composed of solid materials, providing a hot
surface to ignite the combustible gas mixture;
means providing a stream of ambient air directed towards and substantially
surrounding said hot surface ignition means;
emission means, composed of solid materials heated by the combustion flames
of said supply of said gas mixture, for emitting a quantity of radiation
proportional to the heating thereof;
means for detecting radiation, said detecting means detecting radiation
from the emission means and producing therefrom an emission signal
proportional thereto, said detecting means detecting radiation from the
hot surface ignition means and producing therefrom a sail switch signal
proportional thereto;
derivation means for deriving quantities, said derivation means receiving
said emission signal from said detecting means and deriving therefrom an
emission quantity, said derivation means receiving said sail switch signal
from said detecting means and deriving therefrom an ignition quantity; and
means for stopping the supply of said combustible gas mixture when the
emission quantity is less than an predetermined combustion quantity, and
when the ignition quantity is less than a predetermined ignition quantity.
2. The appliance as defined in claim 1, wherein said hot surface ignition
means is substantially positioned away from and out of the combustion
flames of said gas mixture.
3. The appliance as defined in claim 1, further comprising means providing
electrical resistance heating to said hot surface ignition means so as to
achieve a temperature for hot surface ignition of said combustible gas
mixture into said combustion flames.
4. An appliance fired by a combustible gas mixture producing flames upon
ignition, and comprising:
means for supplying said gas mixture to a combustion chamber;
hot surface ignition means, defined by solid materials and contained within
the combustion chamber, providing a hot surface to ignite the combustible
gas mixture into combustion flames, and substantially positioned away from
the combustion flames so as to not be substantially heated thereby;
thermal emission means, composed of solid materials heated by the
combustion flames and contained within the combustion chamber, for
emitting therefrom radiation when heated;
detection means for detecting radiation within the combustion chamber and
for producing a combustion signal proportional thereto; derivation means
for deriving from said combustion signal a first quantity; and;
means providing a stream of ambient air directed towards and substantially
surrounding said hot surface ignition means, said detection means
producing a sail switch signal when surrounded by said stream of ambient
air different from said combustion signal, said derivation means deriving
a second quantity from the sail switch signal and comparing the first and
second quantities to derive a magnitude proportional to a quantitative
measurement of said stream of ambient air.
5. The appliance as defined in claim 4, wherein said hot surface ignition
means emits radiation as it undergoes electrical resistance heating, and
wherein said detection means detects radiation emitted by said hot surface
ignition means and produces a signal proportional to a quantity of
radiation emitted therefrom, and wherein said appliance further includes
means for providing electrical resistance heating to said hot surface
ignition means.
6. A method for monitoring the ongoing combustion of a combustible gaseous
mixture in a gas fired appliance comprising the steps of:
heating an ignitor solid material surface to produce therefrom a quantity
of radiation proportional to the heating thereof;
detecting the quantity of radiation from said ignitor solid material
surface;
producing a signal proportional to the quantity of radiation detected from
said ignitor solid material surface;
deriving from said signal proportional to the quantity of radiation
detected from said ignitor solid material surface a first quantity;
comparing the first quantity to a predetermined range of ignition
quantities; supplying a precombustion stream of said combustible gaseous
mixture to the ignitor solid material surface when the first quantity is
within the predetermined range of ignition quantities;
heating an emitter solid material surface with combustion flames from a
supply of a stream of said combustible gaseous mixture;
detecting a quantity of radiation emitted from the emitter solid material
surface heated by the combustion flames;
producing a signal proportional to the quantity of radiation emitted from
the emitter solid material surface;
deriving from said signal a second quantity; and
directing a stream of ambient air to the combustion flames to shift the
position thereof away from the ignitor solid material surface so as to
lower the radiation emitted therefrom proportional to the absence of
heating thereof by the combustion flames, said directed stream of ambient
air shifting the combustion flames toward the emitter solid material
surface to thereby increase the radiation emitted therefrom proportional
to the heating thereof by the combustion flames.
7. The method as defined in claim 6, further comprising the steps of:
comparing the second quantity to a predetermined range of combustion
quantities; and
preventing the supply of the stream of said combustible gaseous mixture so
as to halt the combustion thereof when the second quantity is outside of
the predetermined range of combustion quantities.
8. A method for igniting a combustible gaseous mixture and for monitoring
the ongoing combustion thereof comprising the steps of:
heating a first solid material surface within a combustion chamber;
supplying a stream of said combustible gaseous mixture to the heated first
surface in the combustion chamber to ignite the combustible gaseous
mixture into combustion flames within the combustion chamber;
halting the heating of the first surface;
directing a stream of ambient air to the combustion flames to shift the
position thereof away from the heated first surface towards a solid second
surface in the combustion chamber to be heated thereby and emit therefrom
a quantity of radiation proportional to the heating thereof by the
combustion flames;
detecting the quantity of radiation from the combustion chamber;
producing a signal proportional to the quantity of radiation detected from
the combustion chamber; and deriving from said signal a first quantity.
9. The method as defined in claim 8, further comprising the steps of:
comparing the first quantity to a predetermined range of combustion
quantities; and
preventing the step of supplying a stream of said combustible gaseous
mixture to the heated second surface while the first quantity is outside
of the predetermined range of combustion quantities.
10. The method as defined in claim 8, which prior to the step of supplying
a stream of said combustible gaseous mixture to the heated first surface,
further comprises the steps of:
detecting a quantity of radiation from the combustion chamber after the
step of heating the first surface;
producing a signal proportional to the quantity of radiation from the
combustion chamber;
deriving from said signal proportional to the quantity of radiation from
the combustion chamber a second quantity;
comparing the second quantity to a predetermined range of ignition
quantities reflective of a temperature sufficient to ignite said
combustible gaseous mixture; and
preventing the step of supplying a stream of said combustible gaseous
mixture to the heated first surface while the second quantity is outside
of the predetermined range of ignition quantities.
11. The method as defined in claim 8, which prior to the step of supplying
a stream of said combustible gaseous mixture to the heated first surface,
further comprises the steps of:
directing a stream of ambient air towards and substantially surrounding
said heated first surface;
detecting a quantity of radiation emitted from the first surface;
comparing the quantity of radiation emitted by the first surface to a
predetermined range of sail switch quantities representative of a
quantitative volume measurement of the stream of ambient air engulfing the
first surface; and
preventing the step of supplying a stream of said combustible gaseous
mixture to the heated first surface while the quantity of radiation from
said heated first surface is outside of the predetermined range of sail
switch quantities.
12. A system for operating a gas fired appliance for combusting into
combustion flames a combustible gas mixture and for producing monitoring
data corresponding to the combustion of the gas mixture comprising:
(a) a combustion chamber;
(b) a supply of a stream of said combustible gas mixture to the combustion
chamber;
(c) a burner element, composed of solid materials, dwelling within the
flames of combustion of said combustible gas mixture in said combustion
chamber;
(d) a discrete electrical element for detecting radiation from both said
burner element and said combustion chamber and for producing a signal
proportional to the detected radiation;
(e) a controller electrically connected to said discrete electrical element
comprising:
(1) means for amplifying said signal output by said discrete electrical
element;
(2) means for converting said amplified signal from an analog to a digital
signal form;
(3) digital processor means for processing said digital signal form; data
memory means for storing digital data; and
(4) program memory means for storing machine-readable instructions utilized
by said digital processor means; wherein said digital processor means
responds to said machine-readable instructions to electronically derive a
quantity proportional to the sensed radiation in the combustion chamber;
(f) a motor driven fan in communication with and controlled by the digital
processor means, the motor driven fan operating to entrain a stream of
ambient air into the combustion chamber, wherein the digital processor
means responds to said machine-readable instructions to electronically
determine if the quantity proportional to the sensed radiation in the
combustion chamber is outside of a predetermined range of quantities, and
controls the operation of the motor driven fan in relation to such
comparison to said predetermined range.
13. The system as defined in claim 12, wherein said digital processor means
is in communication with a means for supplying the supply of a stream of
said combustible gas mixture to the combustion chamber, and wherein the
digital processor means responds to said machine-readable instructions to
electronically determine if the quantity proportional to the detected
radiation in the combustion chamber is outside of said predetermined range
of quantities, and controls the operation of the supply means in relation
to such comparison to said predetermined range of quantities.
14. The system as defined in claim 12, further comprising an ignitor,
wherein said ignitor comprises two electrically conductive rods having an
electrically conductive ignition element therebetween electrically heated
by an electrical current through said ignition element, said ignition
element providing a hot surface ignition for said combustible gas mixture,
said burner element being positioned at upon one of the two electrically
conductive rods and separated from said ignition element.
15. The system as defined in claim 14, wherein the ignitor is in
communication with and controlled by the digital processor means, the
electrically conductive rods being operated by the digital processor means
to electrically heat the ignition element therebetween so as to ignite the
stream of combustible gas mixture into combustion flames in the combustion
chamber, wherein the digital processor means responds to said
machine-readable instructions to electronically determine if the quantity
proportional to the sensed radiation in the combustion chamber is outside
of said predetermined range of quantities, and controls the ignitor in
relation to such comparison to said predetermined range of quantities.
16. The system as defined in claim 12, further comprising a display means,
in communication with the controller, for outputting a visual display of
the quantity proportional to the sensed radiation in the combustion
chamber.
17. The system as defined in claim 14, wherein the stream of ambient air is
directed towards and substantially surrounds said ignition element, said
discrete electrical element detecting radiation from the ignition element
and producing a sail switch signal proportional to the radiation therefrom
when said ignition element is surrounded by said stream of ambient air,
said digital processor means:
(a) responding to said machine-readable instructions to electronically
derive a quantity proportional to the sail switch signal;
(b) comparing said quantity proportional to the sail switch signal with a
predetermined range of sail switch quantities; and
(c) controlling the ignitor in relation to such comparison of the sail
switch signal to said predetermined range of sail switch quantities.
18. An appliance fired by a combustible gas mixture producing combustion
flames upon ignition, and comprising:
(a) means for supplying a stream of said combustible gas mixture; a
combustion monitor comprising:
(1) an electrically conductive ignition element electrically heated by an
electrical current, said ignition element providing a hot surface ignition
for said combustible gas mixture, said ignition element emitting a
quantity of radiation proportional to the heating thereof;
(2) a discrete electrical element for detecting radiation emitted from said
ignition element and producing an ignition signal proportional thereto;
and
(3) derivation means for deriving an ignition quantity from said ignition
signal;
(b) means providing a stream of ambient air directed towards said ignition
element for cooling the ignition element and thereby reducing the quantity
of radiation emitted therefrom; and
(c) means for controlling the means for supplying a stream of said
combustible gas mixture based upon a comparison of the ignition quantity
to a predetermined range of ignition quantities.
19. An appliance as defined in claim 18, wherein the combustion monitor
further comprises:
an emitter element, composed of solid materials, positioned within the
combustion flames of said combustible gas mixture said emitter element
emitting a quantity of radiation proportional to the heating thereof,
wherein:
(1) said discrete electrical element detects radiation emitted from said
emitter element and produces an emitter signal proportional thereto;
(2) said derivation means derives an emitter quantity from said emitter
signal; and
(3) said means for controlling the means for supplying a stream of said
combustible gas mixture controls the means for supplying a stream of said
combustible gas mixture based upon a comparison of the emitter quantity to
a predetermined range of emitter quantities.
20. Appliance as defined in claim 19, wherein the means for supplying a
stream of said combustible gas mixture shifts the position of the
combustion flames so that the emitter element is within the combustion
flames and the ignition element is away from the combustion flames.
21. An appliance as defined in claim 19, wherein the combustion monitor
further comprises:
a pair of electrically conductive rods, said electrically conductive
ignition element being electrically heated by an electrical current
passing therethrough via said pair of electrically conductive rods, and
wherein said discrete electrical element is mounted upon said pair of
electrically conductive rods.
22. An appliance as defined in claim 21, wherein the emitter element is
positioned upon at least one of the two electrically conductive rods and
is separate from said ignition element.
23. An appliance as defined in claim 19, wherein at least one of the
emitter element and the ignitor element is substantially composed of a
material having a melting point above 1200.degree. F. and selected from
the group consisting of aluminum-nickel alloys, iron-chromium-aluminum
alloys, and stainless-steel having an aluminum-silicon additive, said
material.
24. An appliance as defined in claim 19, wherein at least one of the
emitter element and the ignitor element is substantially composed of a
material having a composition of between 4 and 5% aluminum, about 22%
chromium, and iron.
25. An appliance as defined in claim 19, wherein the means providing a
stream of ambient air shifts the position of the combustion flames so that
the emitter element is within the combustion flames and the ignition
element is away from the combustion flames.
26. An appliance fired by a combustible gas mixture producing combustion
flames upon ignition, and comprising:
(a) means for supplying a stream of said combustible gas mixture; a
combustion monitor comprising:
(1) an electrically conductive ignition element electrically heated by an
electrical current, said ignition element providing a hot surface ignition
for said combustible gas mixture, said ignition element emitting a
quantity of radiation proportional to the heating thereof;
(2) an emitter element, composed of solid materials, dwelling within the
combustion times of said combustible gas mixture said emitter element
emitting a quantity of radiation proportional to the heating thereof,
(3) a discrete electrical element for detecting radiation emitted from said
ignition element and producing an ignition signal proportional thereto,
and wherein said discrete electrical element detects radiation emitted
from said emitter element and produces an emitter signal proportional
thereto; and
(4) derivation means for deriving an ignition quantity from said ignition
signal, and wherein said derivation means derives an emitter quantity from
said emitter signal;
(b) means providing a stream of ambient air directed towards said ignition
element for cooling the ignition element and thereby reducing the quantity
of radiation emitted therefrom; and
(c) means for controlling the means for supplying a stream of said
combustible gas mixture based upon a comparison of the ignition quantity
to a predetermined range of ignition quantities, and based upon a
comparison of the emitter quantity to a predetermined range of emitter
quantities.
27. An appliance fired by a combustible gas mixture producing combustion
times upon ignition, and comprising:
means for supplying said combustible gas mixture;
means having a hot surface for igniting the combustible gas mixture to
produce said combustion times, said hot surface consisting essentially of
a metal material;
means for shifting said combustion flames away from said hot surface
subsequent to ignition of the combustible mixture into said combustion
flames;
means for detecting radiation, said detecting means detecting radiation
from the hot surface and producing therefrom an ignition signal
proportional thereto;
derivation means for deriving quantities, said derivation means receiving
said ignition signal from said detecting means and deriving therefrom an
ignition quantity; and
means for stopping the supply of said combustible gas mixture when the
ignition quantity is less than a selected ignition quantity.
28. The appliance as defined in claim 27, wherein said means for shifting
said combustion flames away from said hot surface subsequent to ignition
of the combustible mixture into said combustion flames comprises:
(a) a tube having a hollow interior, wherein said hot surface is situated
outside of said hollow interior of said tube, said tube comprising:
(i) a gas inlet situated at an end of said tube;
(ii) a flame outlet situated at an end of said tube opposite of said gas
inlet;
(iii) an air inlet between said gas inlet and said flame outlet, said air
inlet being closer to said gas inlet than said flame outlet; and
(iv) a combustible gas mixture outlet between said gas inlet and said time
outlet, said combustible gas mixture outlet being:
(A) closer to said flame outlet than said gas inlet;
(B) substantially smaller than said air inlet; and
(C) situated proximal to said hot surface;
(b) whereby in an operational mode of said appliance:
(i) said hollow interior of said tube receives:
(A) a gas through said gas inlet; and
(B) ambient air through said air inlet;
(ii) said ambient air and said gas combining in said hollow interior of
said tube to form said combustible gas mixture;
(iii) at least a portion of said combustible gas mixture exits the tube
through the combustible mixture outlet to contact said hot surface;
(iv) said hot surface ignites the combustible gas mixture exiting the
hollow interior of the tube through the combustible mixture outlet to
produce said combustion flames, and
(v) subsequent to ignition of the combustible mixture into said combustion
flames, said combustion flames shift away from said hot surface through
said combustible mixture outlet to exit said tube through said flame
outlet.
29. The appliance as defined in claim 27, wherein said means for shifting
said combustion flames away from said hot surface subsequent to ignition
of the combustible mixture into said combustion flames comprises means
providing a stream of air directed towards and substantially surrounding
said hot surface to shift said combustion flames shift away from said hot
surface.
30. The appliance as defined in claim 29, wherein said means providing a
stream of air directed towards and substantially surrounding said hot
surface ignition comprises a motor driven fan operating to entrain a
stream of air towards the combustion flames so as to shift said combustion
flames shift away from said hot surface.
31. The appliance as defined in claim 27, further comprising:
(a) means providing a stream of air directed towards and substantially
surrounding said hot surface to shift said combustion flames shift away
from said hot surface for cooling the ignition element and thereby
reducing the quantity of radiation emitted therefrom; and
(b) means for controlling the means for supplying a stream of said
combustible gas mixture based upon a comparison of the ignition quantity
to a predetermined range of ignition quantities.
32. An appliance as defined in claim 27, further comprising:
an emitter element, composed of solid materials, positioned within the
combustion flames of said combustible gas mixture said emitter element
emitting a quantity of radiation proportional to the heating thereof,
wherein:
(1) said means for detecting radiation detects radiation emitted from said
emitter element and produces an emitter signal proportional thereto;
(2) said derivation means derives an emitter quantity from said emitter
signal; and
(3) said means for stopping the supply of said combustible gas mixture
controls the means for supplying a stream of said combustible gas mixture
based upon a comparison of the emitter quantity to a selected range of
emitter quantities.
33. An appliance fired by a combustible gas mixture producing combustion
flames upon ignition, and comprising:
means for supplying said combustible gas mixture;
means having a hot surface for igniting the combustible gas mixture to
produce said combustion flames, said hot surface consisting essentially of
a metal material; and
means for shifting said combustion flames away from said hot surface
subsequent to ignition of the combustible mixture.
34. The appliance as defined in claim 33, further comprising:
means for detecting radiation, said detecting means detecting radiation
from the hot surface and producing therefrom an ignition signal
proportional thereto;
derivation means for deriving quantities, said derivation means receiving
said ignition signal from said detecting means and deriving therefrom an
ignition quantity; and
means for stopping the supply of said combustible gas mixture when the
ignition quantity is less than a selected ignition quantity.
35. The appliance as defined in claim 33, wherein said means for shifting
said combustion flames away from said hot surface subsequent to ignition
of the combustible mixture comprises:
(a) a tube having a hollow interior, wherein said hot surface is situated
outside of said hollow interior of said tube, said tube comprising:
(i) a gas inlet situated at an end of said tube;
(ii) a flame outlet situated at an end of said tube opposite of said gas
inlet;
(iii) an air inlet between said gas inlet and said flame outlet, said air
inlet being closer to said gas inlet than said flame outlet; and
(iv) a combustible gas mixture outlet between said gas inlet and said flame
outlet, said combustible gas mixture outlet being:
(A) closer to said flame outlet than said gas inlet;
(B) substantially smaller than said air inlet; and
(C) situated proximal to said hot surface;
(b) whereby in an operational mode of said appliance:
(i) said hollow interior of said tube receives:
(A) a gas through said gas inlet; and
(B) ambient air through said air inlet;
(ii) said ambient air and said gas combining in said hollow interior of
said tube to form said combustible gas mixture;
(iii) at least a portion of said combustible gas mixture exits the tube
through the combustible mixture outlet to contact said hot surface;
(iv) said hot surface ignites the combustible gas mixture exiting the
hollow interior of the tube through the combustible mixture outlet to
produce said combustion times, and
(v) subsequent to ignition of the combustible mixture into said combustion
flames, said combustion flames shift away from said hot surface through
said combustible mixture outlet to exit said tube through said flame
outlet.
36. The appliance as defined in claim 33, wherein said means for shifting
said combustion flames away from said hot surface subsequent to ignition
of the combustible mixture into said combustion flames comprises means
providing a stream of air directed towards and substantially surrounding
said hot surface to shift said combustion flames shift away from said hot
surface.
37. The appliance as defined in claim 36, wherein said means providing a
stream of air directed towards and substantially surrounding said hot
surface ignition means comprises a motor driven fan operating to entrain a
stream of air towards the combustion flames so as to shift said combustion
flames shift away from said hot surface.
38. The appliance as defined in claim 33, further comprising:
(a) means providing a stream of air directed towards and substantially
surrounding said hot surface to shift said combustion flames shift away
from said hot surface for cooling the ignition element and thereby
reducing the quantity of radiation emitted therefrom; and
(b) means for controlling the means for supplying a stream of said
combustible gas mixture based upon a comparison of the ignition quantity
to a predetermined range of ignition quantities.
39. An appliance as defined in claim 27, further comprising:
an emitter element, composed of solid materials, positioned within the
combustion flames of said combustible gas mixture said emitter element
emitting a quantity of radiation proportional to the heating thereof,
wherein:
(1) said means for detecting radiation detects radiation emitted from said
emitter element and produces an emitter signal proportional thereto;
(2) said derivation means derives an emitter quantity from said emitter
signal; and
(3) said means for stopping the supply of said combustible gas mixture
controls the means for supplying a stream of said combustible gas mixture
based upon a comparison of the emitter quantity to a selected range of
emitter quantities.
Description
A portion of the disclosure of this patent document contains material to
which a claim of copyright protection is made. The copyright owner has no
objection to the reproduction by anyone of the patent document or the
patent disclosure as it appears in the Patent and Trademark Office patent
file or records, but reserves all other rights with respect to the
copyrighted work.
BACKGROUND
I. Field of the Invention
This invention relates to fuel gas ignition and combustion monitoring
systems, and more particularly to a system and method which utilize an
electronically monitored ignition and combustion monitoring device for
controlling the operation of a gas fired appliance.
II. Background Art
Fuel gas is used in a wide range of gas fired appliances including ranges,
stoves, gas refrigerators, barbecue pits, gas fired fireplaces, clothes
dryers and water heaters. A conventional mechanism for igniting the fuel
supplied to the gas fired appliances is a high voltage spark created by a
spark generator. In spark ignition, two separated conductors have a
voltage potential difference therebetween sufficient to induce a spark to
jump the gap separating the two conductors. A third rod is engulfed in the
flames of combustion and is used by the conductivity thereof to ascertain
ongoing combustion. The conductivity of the air and third rod within the
combustion envelope verifies that combustion is ongoing.
A problem known to spark generation equipment is the large draw of power
required to make the spark jump the gap. This is particularly true if, by
some happenstance, the gap size is increased between the two conductors.
Additionally, the spark causes electromagnetic interference which tends to
be a nuisance to radios, television sets, personal computers, and other
electronic appliances in the area. In light of such a problem with spark
ignition systems, it would be an advance in ignition systems for gas fired
appliances to provide an ignition system that meets both conventional and
developing telecommunication standards for electromagnetic interference
omission.
Gas fired appliances are frequently controlled by microprocessors. Such
microprocessors can be interfered with by spark generators. Additionally,
the high voltages characteristics of spark generation can be deleterious
to semiconductors in the control system of the appliance, as such high
voltages can lead to the breakdown of semiconductor parts therein. Thus,
the reliability of semiconductor components for controlling gas fired
appliances may be jeopardized.
Another problem known to spark generators for the ignition of gas fired
appliances is that the spark that is generated is consistent in both
standard magnitude and size for an average environment of relative
humidity. Consequently, in very high ambient relative humidity, the spark
being generated may be insufficient to cause proper ignition of the fuel
gas. Particulates in the air, accumulations of soot, and variations in
altitude, in addition to the foregoing, can hinder spark generation and
the ignition of the fuel gas.
An option to spark ignition for gas fired appliances is circuit ignition
using a hot carbide surface, such as silicon carbide. Circuit ignitions
are, however, typically more expensive than spark ignition systems.
Carbides used for hot surface ignition of combustible fuel gases can
withstand very high temperatures, have a high melting point, and are
corrosion resistant. A difficulty with such hot surface ignition systems
is the necessity of having to bond or otherwise weld the carbide to a
metallic system that conducts electricity. This type of welding is
necessary to electrically resistance heat the carbide, but is both
expensive and difficult in that it requires very high temperatures to
accomplish. Further, the carbide providing the hot surface ignition tends
to be quite brittle and thus frangible and unreliable in physically
non-fragile environments, such as is known to recreational vehicle
appliances.
From the foregoing, it can be seen that it would be an advance in gas fired
appliance ignition art to provide an ignition system that is inexpensive,
does not cause electromagnetic interference with controllers of the gas
fired appliance, and withstands heavy-duty use without breaking.
Gas fired appliances may have an ignition and combustion system that is
regulated by a controller that causes the correct order, correct timing,
and safety features thereof to be cooperating as subsystems of the
appliance. Such modem gas fired appliances consist of a gas supply system,
an ignition and combustion verification system, a safety cut-off valve to
the gas supply system, and a heat extraction or heat exchange system. It
is the goal of such controllers to provide transparent operation of the
gas fired appliance to the user. By way of example, such a controller may
control the combustion mix of air and fuel gas so that it is neither too
lean nor too rich, but rather combusts most efficiently. Such a controller
may regulate the operation of an electrically activated solenoid valve
which opens and closes the gas flow to the appliance so that the right
amount of gas at the right velocity is mixed into the combustion area or
mixing space for combustion.
In the case of furnaces and other gas fired appliances requiring an air
delivery system, a blower fan may also be operated by a controller. Should
there ever be an extinguishment of combustion, a blower fan may be
operated by the controller so as to purge the combustion area free of
combustible fuel gas and thereby prevent a build up of same and a
subsequent explosion. When the controller operates the blower fan
following extinguishment of a flame, a safety timing period is provided
between the receipt of the controller of a request of a thermostat to
start opening the gas valve, and the subsequent opening of the gas valve
supplying fuel gas to the combustion area. Thus, the controller may
control the timing of the actual delivery and purging of the combustible
fluid contents of the combustion area.
Another important function which may be controlled by a controller, and may
also be accomplished by mechanical systems, is that of a sail switch which
measures air flow to the combustion area. A sail switch is a mechanical
switch that is switched on or off by the flow or non-flow of air. The
switch signals the controller to turn off the supply of fuel gas if air
flow to the combustion area has been terminated. By way of example, an
obstruction in the air intake to the blower fan may cause a rich fuel gas
mixture in the combustion area due to an absence of air coming through the
air intake. A sail switch would prevent such a problem by giving an
indication of air intake malfunctioning, which indication is acted on by
the controller to prevent the fuel gas from flowing into the combustion
chamber. Thus, gas is not combusted in the case where air is not being
provided to the combustion area, or is not being provided so as to remove
heat from the combustion chamber. The sail switch helps to indicate that
air is flowing to reduce the heat of combustion, and thus prevent the
burning up of heat exchanger components of the gas fired appliance.
In short, the sail switch is an anemometer to measure the amount of air
that is being delivered to the combustion area. The sail switch, by its
function of assuring that the appliance will not operate without a proper
air flow to the combustion chamber, prevents a typical problem of air flow
blockage or redirections of the air which may in turn cause the flames of
redirection of the flames of combustion to be redirected to an area that
is hazardous to the appliance.
While prior art sail switch techniques have been widely used with success,
there is still a serious risk of human error when using such systems. The
sail switches used on such gas fired furnaces are often prone to
mechanical failure due to environmental conditions, and due to corrosion
over time as the appliance ages. Thus, improper sail switch operation may
occur. Accordingly, there is a need for a gas fired appliance that safely
and accurately acknowledges a proper in take of air to the combustion area
so as to assure that a flue is not blocked. The system and method of the
present invention provide an effective solution to these problems which
has not heretofore been fully appreciated or solved.
A controller for a gas fired appliance may also be in electrical
communication with a limit switch or ECO. The ECO switch cuts off power so
as to close the gas supply valve whenever certain critical areas of the
appliance reach a maximum tolerable temperature. In the case of furnaces
and other gas fired appliances having a blower fan to the combustion
chamber, a timing relay is also operated in conjunction with the ECO so
that there is a purging of the gas combustion area following the shut off
of electrical power to the appliance.
An ignition control board or other appliance controller device,
incorporates the foregoing functions of monitoring the ignition,
combustion, and ongoing operation of a gas fired appliance. It would be an
advance in art to provide a safe and reliable integrated ignition and
combustion control system that overcomes foregoing problems while
intercoordinating typical functions provided by a gas fired appliance.
BRIEF SUMMARY AND OBJECTS OF THE INVENTION
The system and method of the present invention have been developed in
response to the present state of the art, and in particular, in response
to the problems and needs in the art not heretofore fully or completely
solved by ignition and combustion systems for gas fired appliances. It is
not intended, however, that the system and method of the present invention
will necessarily be limited solely to ignition and combustion control,
since they will also find useful application with potentially many kinds
of gas fired appliances which require the control of various operational
aspects, including temperature regulation, burn efficiency, and
operational communications. Thus, it is an overall object of the present
invention to provide a system and method which provide for the safe and
efficient operation of a gas fired appliance.
Another important object of the present invention is to provide a system
and method whereby state of the art electronic technology can be utilized
to assist the safe and efficient operation of a gas fired appliance.
Another important object of the present invention is to provide a gas
ignitor system and method of electronic monitoring fuel gas ignition which
increases the convenience and safe utilization of gas fired appliances in
general.
These and other objects and features of the present invention will become
more fully apparent from the following more detailed description taken in
conjunction with the drawings and claims, or may be learned by the
practice of the invention.
Briefly summarized, the foregoing and other objects are achieved in an
electronically monitored ignition system and method for combustible gases
used in gas fired appliances. By way of example, such appliances include
ranges, stoves, gas refrigerators, or gas appliances in general. The novel
ignition and combustion control system and method is capable of igniting
combustible gases as well as detecting a flame resulting from such
ignition.
The ignition and flame sensing system is used in a heat exchange system
that employs a fuel-to-air mixing mechanism. The gas mixture is fed to an
electrically heated solid material providing a hot surface ignition for
the mixture. The hot surface ignition on the electrically heated solid
material produces a flame by combustion of the fuel. Energy of the flame
from the combustion heats a solid material that emits radiation when
heated. The flame heated solid material may be the same as, or different
from, the electrically heated solid material.
Radiation from the solid material is detected by an infrared sensor and is
monitored by associated circuitry. The infrared sensor may be focused to
detect radiation from either or both of the electrical and flame heated
solid material. As mentioned, the electrical and flame heated solid
materials may also be one and the same. Alternately, multiple infrared
sensors with associated circuitry may also be provided to focus on a
separate one of the electric or flame heated solid materials.
Radiation emitted from the electric or flame heated solid materials is
indicative of the temperature of the solid material. The temperature of
the solid material is effected by the degree of its electrical or flame
heating. As such, circuitry associated with the infrared sensor can verify
that the electrically heated solid material is both operational and hot
enough to function in hot surface ignition. Additionally, the infrared
sensor and associated circuitry can prove that combustion was successfully
achieved by the electrically heated solid material serving as a point of
hot surface ignition.
The temperature of the electrically heated solid material can be lowered by
the degree to which an air flow engulfs the same so as to lower its
temperature by a cooling off effect. As such, the infrared sensor and
associated circuitry can verify that a blower fan associated with the gas
fired appliance is being properly operated so as to cause a proper air
flow into a combustion chamber in which the electrically heated solid
material is also situated.
The temperature of the flame heated solid material can be affected by the
existence and efficiency of the flame that heats the solid material. The
degree of infrared radiation being emitted by the flame heated solid
material is indicative of how efficient the burning of the flame is, as
well as being indicative of the temperature of the combustion area. Such
efficiency of radiation emission may be effected by a poor air-to-fuel
mixture due to a blockage in air intake, contaminated fuel gas, and
atmospheric conditions including air borne particulates and high relative
humidity, any one on combination of which may lower the efficiency of the
combustion and thus the emission of radiation that is detected and
verified by the infrared sensor and it associated circuitry.
A further capability of the one or more infrared sensors in the inventive
method and system is the ability to detect excessive infrared emission
characteristic of weakening or failing structural material of the gas
fired appliance, such as a broken seam or a hole in a combustion chamber
of a gas fired furnace. Weakened materials that are heated, such as sheet
metal, give off excessive infrared energy during failure.
In general summary, the inventive method and system coordinates on-going
combustion by the detection of infrared emissions emanating from a solid
material engulfed within and being heated by a flame of combustible gas,
where an infrared sensor is focused by line of sight upon the solid
material that is emitting infrared radiation in proportion to the
temperature of the solid material, the solid material being heated by a
flame in a combustion area, the flame heated solid material being constant
in surface area and composition, and upon which an infrared sensor is
focused for the purpose of evaluating the presence and efficiency of the
combustion of combustible fuel, the circuitry associated with the infrared
sensor receiving a signal from the infrared sensor and using such signal
for verifying the presence and continuity of a flame in a combustion area,
which radiation is monitored by the infrared sensor as a means of deriving
therefrom the presence and efficiency of the combustion of a combustible
gas that is used to heat the infrared radiating solid material, where the
monitored efficiency of combustion is used by the circuitry associated
with the one or more infrared sensor(s) to control operational parameters
including the input of fuel and air to the combustion chamber.
The circuitry associated with one or more infrared sensors of the inventive
system may be characterized as an electronic circuit means or a
controller. The controller is responsive to a control signal produced by
the infrared sensor for controlling a valving means which supplies fuel to
the combustion chamber.
Aspects of the inventive method and system relating to the ignition of
combustible fuel may be considered as separate functional aspects relating
to on-going combustion of the combustible fuel.
Structurally, in a preferred embodiment, the inventive ignition and
combustion control system consists of two rods which are connected
together by a first filament material. Preferably, although optionally,
the first filament material is made from KANTHAL.TM.. This material is
basically an aluminum and nickel alloy that has a high melting point.
Alternatively, the material may be stainless-steel with an aluminum
silicone additive such that its melting point is high (i.e. above 1,200
degrees Fahrenheit).
The first filament material is wrapped with four or five turns around each
of the two rods, and is then welded using spot welds to the two rods. The
proper electrical resistance for hot surface ignition of combustible gas
in the system is determined as a function of the number of turns in the
first filament material between the two rods. In this way, the hot surface
ignition area on the first filament material can be optimized for the
combustible gas having contact therewith as an electrical current
resistance heats the first filament material between the two rods.
Preferably, the first filament material is within the line of sight of the
infrared sensor.
Preferably, one of the two rods is longer than the other and may have
welded at or near an end thereof a second filament material that is coiled
or wrapped there around. When so wrapped, the larger rod act as a heat
sink for the second filament material. Alternatively, the longer rod can
be either straight or bent at an angle without a second filament material
wrapped there around, yet still extend beyond the length of the shorter
rod. Regardless of the form of the larger rod, it is intended that the end
extending past the end of the shorter rod be within the line of sight of
the infrared sensor and also be heated by a flame in the combustion area
of the appliance which is the product of the combustion of the fuel gas.
Both the first filament material between the two rods and the second
filament material at an end of the longer rod are preferably of low
thermal mass and have a rapid response to heating such that infrared
emissions can be detected by a relatively inexpensive infrared sensor. The
longer of the two rods, when lacking a second filament material, may be
composed of materials having a rapid response to emit infrared radiation
through heating, such as KANTHAL.TM.. The geometry of end of the longer
rod may also be thinned to have a low thermal mass so as to give a rapid
infrared radiation emission upon heating of the sallie.
The first filament material extending between the two rods, referred to
herein as the first radiator, is initially heated with an electrical
current passed therebetween. The electrical current passing through the
first radiator causes the first radiator to be raised to an ignition
temperature for the combustible gas. The elevated temperature of the first
radiator, acting as a hot surface ignitor, ignites the combustible gas.
The inventive ignition system is capable of verifying that the first
radiator is hot enough to ignite the combustible gas by detecting
emissions of infrared radiation emanating from the first radiator material
due to the resistance heating thereof.
In an alternative embodiment, the next step following resistance heating of
the first radiator is to actuate a blower fan to direct a stream of air
into a combustion area where the resistance heated first radiator is
located. The stream of air causes a slight cooling of the first radiator.
This cooling is detected by a decrease in infrared radiation being emitted
by the first radiator, which decrease is detected by the infrared sensor
and associated circuitry. Such a decrease in the emission of infrared
radiation is an indication that the blower fan is properly delivering air
into the combustion area. Such a embodiment is preferred in confined areas
of combustion for the fuel gas, such as is found in gas fired furnaces.
Upon verification of achieving the ignition temperature by the first
radiator, the current between the rods is cut off, the first radiator
cools down, and the appliance is controlled to supply additional
combustible gas to the flame. In some preferred embodiments of the
inventive system and method, the flow of combustible gas tends to shift
and extend the length of the flame to engulf the length of the longer rod
extending beyond the shorter rod, which length may have the second
filament material thereon. The extended flame causes the extended length
of the second rod, and/or second filament material thereon, to heat up.
Upon heating by the combustion flames, the extended length of the second
rod, and/or second filament material, these being referred to herein as
the second radiator, begins to emit infrared energy which is then detected
by the infrared sensor and it associated circuitry. Once the flame is
shifted in position and elongated by a supply of gas and air mixture that
is under greater pressure that the initial ignition pressure, the first
radiator is no longer resistance heated or within the times of the
combustible gas. Thus, the infrared sensor substantially detects only
infrared energy being emitted by the second radiator, as the first
radiator is no longer resistance heated or within the heating zone of
ongoing combustion.
Henceforth, the infrared sensor witnesses the on-going combustion of
combustible gases as evidenced by the emission of infrared energy from the
second radiator. As such, the second radiator serves as the solid material
object upon which the infrared sensor focuses so that its associated
circuitry can verify the presence of a flame of combustible gas or the
absence thereof. The infrared sensor and circuitry also verifies, by the
intensity of infrared radiation, a measure of bum efficiency of the
combustible fuel as well as ascertaining potential material failure and
weakening of the structural elements of the combustion area.
It is contemplated that the invention involves microprocessor control of
the gas fired appliance for the purposes of controlling the flow of gas to
the appliance, controlling the temperature of the first radiator for the
purpose of ignition of the combustible gas, as well as other
microprocessor controls which monitor and automatically adjust the general
operation of the gas fired appliance.
As an example of the type of control that the inventive ignition and
combustion control system and method is capable of, should the flame of
combustible gas extinguish or otherwise perform substandardly, then a
supply valve for the flow of gas to the appliance can be modulated closed
by microprocessor control when a substandard signal from the infrared
sensor is detected based upon the quantity of emitted radiation from the
second radiator. After the flow of gas has been cut off, the
microprocessor can then control the ignition system to attempt one or more
retries to ignite the combustible gas by signals derived from the first
radiator after the extinguishment of the flames of the combustible gas is
verified by signals to the microprocessor derived from the second
radiator.
A further concept of the type of control capable with the inventive system
and method is the ability to sense the effect of a flow of air upon the
first radiator. To do so, the general principle is observed that the
infrared energy emitted by a heated solid material is inversely
proportional to the cooling effect of air upon the heated solid material.
The amount of cooling air to which the heated solid material is exposed is
proportional to the infrared energy emitted. As such, infrared energy
emitted by a heated radiator, with the infrared sensor and associated
circuitry, function as a form of anemometer to measure air velocity.
In further application, the efficiency of the combustion in the appliance
is also effected by air flow and is indicated by the degree of infrared
radiation emitted from the heated solid material, which infrared radiation
is detected by the infrared sensor and circuitry associated therewith. By
way of example, should the air flow into the gas combustion chamber become
blocked during ongoing combustion, then the diminished air flow will cause
a decreased efficiency in the combustion of combustible gas. This
efficiency decrease will cause the second radiator, which is engulfed in
flames, to emit less infrared radiation due to the decrease of gas
combustion. The infrared sensor will detect the decrease in the emission
of infrared energy from the second radiator and the appliance operational
parameter, such as the flow of combustible gas thereto, is then adjusted
using software control via a microprocessor associated with the inventive
system. Thus, the infrared sensor, associated circuitry, and the second
radiator are used in the inventive system and method to monitor
obstructions of air flow to the combustion chamber.
The monitoring of air flow performs the function of a conventional sail
switch, and is also used to maximize the efficiency of the combustion of
the combustible gas. By controlling both air and fuel feeding to the
combustion area, a comprehensive gas fired appliance control and
efficiency system is achieved.
As a further extension and safety feature of the invention, the infrared
sensor can be used to detect abnormal infrared emissions which may signal
that the materials from which the appliance is constructed have reached a
critical temperature that is near the point of fatigue or cracking. Upon
such abnormal emissions of radiation which are detected by the infrared
sensor and circuitry, microprocessor control of the appliance initiates a
process to decrease or otherwise turn-off the feed of combustible gas to
the appliance via a gas valve modulation system.
While it is preferable, the infrared sensor need not be physically situated
in direct view of either the first or second radiators. Rather, optical
fibers having an end directed toward such radiators can be used to direct
the infrared radiation to an infrared sensor that is located remotely from
the source of the infrared radiation. By way of example, an infrared
sensor on a gas fired stove can be focused upon an end of one or more
optical fibers having an opposite end directed at solid material engulfed
within a flame so as to assist therethrough infrared radiation therefrom.
The inventive ignition system has the versatility of being able to detect a
variety of combustible gases including propane, natural gas, or liquid
petroleum gas. Once the type of combustible gas is known, the appropriate
range of infrared radiation from the first and second radiators that is
applicable to the ignition and combustion of such gas can then be set as a
process variable in the microprocessor control for the corresponding gas
fired appliance.
In summary, the device may be characterized in main preferred embodiments
thereof as a system and method having an electronic ignition control board
for the purpose of igniting and monitoring a gas fired appliance operation
by infrared sensing of a solid infrared emitting material as a mean of
gauging the presence, absence, ignition potential for, and efficiency of a
flame of combustible gas.
The inventive system is easy to manufacture while at the same time
providing improved overall safety in the ignition and accurate
determination of the existence and the quality of on-going combustion of
fuel gas in a gas fired appliance.
BRIEF DESCRIPTION OF THE DRAWINGS
The presently preferred embodiments and the presently understood best mode
of the invention will be described with additional detail through use of
the accompanying drawings, wherein corresponding structural parts are
designated by the same reference numerals throughout, and in which:
FIG. 1A is a preferred embodiment of the inventive hot surface ignition and
combustion monitoring device;
FIG. 1B shows an alternative preferred embodiment of the inventive hot
surface ignition and combustion monitoring device positioned above and
adjacent to a burner tube with the ignition coil thereof protruding from
an end of the burner tube;
FIG. 1C shows the alternative preferred embodiment of the inventive hot
surface ignition and combustion monitoring device positioned above and
adjacent to a burner tube, wherein the ignition coil thereof is positioned
above and adjacent to an ignition hole providing an inlet for ambient air
to the inside of the burner tube;
FIG. 2 is a preferred embodiment of an inventive gas fired furnace
incorporating the inventive ignition and combustion monitoring device;
FIG. 3 is preferred embodiment of an inventive gas fired water heater
incorporating the inventive ignition and combustion monitoring device;
FIG. 4 is a functional block diagram which schematically illustrates the
primary components of one presently preferred electronic circuit used in
connection with the electronic controller incorporated into the inventive
ignition and combustion monitoring system;
FIGS. 5A-5D taken together constitute a detailed electrical schematic
diagram which illustrate, as an example, a presently preferred embodiment
and one presently understood best mode for implementing the electronics of
the system and method of the present invention in a gas fired furnace;
FIGS. 6-14, 15a-15h, and 16-19 taken together illustrate flow charts
showing one presently preferred method for programming the digital
processor of the inventive ignition and combustion monitoring system in
accordance with the method of the present invention for controlling a gas
fired furnace.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
III. The System
A. The Presently Preferred Inventive Ignitor and Combustion Monitor within
Gas Fired Appliances: (FIGS. 1A-3).
FIG. 1A depicts a preferred embodiment of the inventive device referred to
hereinafter as an ignitor, generally indicated at 10. Ignitor 10 has a
first electrically conductive rod 12 and a second electrically conductive
rod 14 with an electrically conductive ignition coil 16 therebetween. A
voltage potential between first conductive rod 12 and second conductive
rod 14 causes ignition coil 16 to undergo electrical resistance heating.
When ignition coil 16 is heated, it begins to glow and emit infrared
radiation. The temperature to which ignition coil 16 is heated is
sufficient for hot-surface ignition of a combustible gas that comes in
contact with ignition coil 16.
While ignition coil 16 is being electrically heated, an IR detector 18
detects infrared radiation being emitted by ignition coil 16. During the
time that ignition coil 16 is being electrically heated, IR detector 18
detects the emission of infrared radiation therefrom. Preferably, IR
detection 18 has ignition coil 16 within its line of sight.
After a predetermined period of time, electrical current supplied to
ignition coil 16 by first and second conductive rods 12, 14 is terminated.
This predetermined period of time is equal to or greater than the period
of time necessary for ignition coil 16 to ignite the combustible gaseous
fuel coming in contact therewith. When electrical current ceases to flow
through ignition coil 16, ignition coil 16 will no longer emit a high
degree of infrared radiation as it begins to cool. The cooling and
emission of a lesser amount of radiation by ignition coil 16 will be
detected by IR detector 18 as ignition coil 16 cools.
After ignition coil 16 has ignited by a hot surface thereon the combustible
gaseous fuel, the flames of combustion will be directed towards combustion
and emission region 20 seen in phantom in FIG. 1A.
The physical arrangement and placement of combustion and emission region 20
is such that the flames from the combustion of gaseous fuel will
essentially heat only combustion and emission region 20 and will not
substantially heat ignition coil 16. The gradation in temperature between
ignition coil 16 and combustion and emission region 20 is preferable due
to the physical arrangement of the fuel being fed to combustion and
emission region 20. Alternatively, a blower fan may direct air so as to
shift the flames of combustion. The net effect of this physical
arrangement or flame shifting is that infrared radiation will be emitted
from combustion and emission region 20 to a substantially larger degree
than that which is emitted from ignition coil 16.
As combustion and emission region 20 is heated by the flames produced
through the combustion of gaseous fuel, solid materials that are within
combustion and emission region 20 will begin to heat up. Preferably, the
solid material that is within combustion and emission region 20 will be of
the type that emits a high degree of infrared radiation when heated. As
seen in FIG. 1A, an emission coil 22 is wrapped around and upon an
emission element 24, both of which are within combustion and emission
region 20. Emission coil 22 is preferably a relatively thin coil that
withstands heating for an extended period of time without failure.
Emission element 24 is similarly able to withstand heating over a lengthy
period of time without disintegration or otherwise failing.
While the materials within combustion and emission region 20 are being
heated to the point of emitting infrared radiation, IR detector 18 detects
infrared radiation being emitted from combustion and emission region 20.
By the detection of infrared radiation coming from combustion and emission
region 20, IR detector 18 can determine whether a successful combustion
has taken place and is ongoing. Preferably, combustion and emission region
20 and, specifically, emission coil and elements 22, 24, are within the
line of sight of IR detector 18.
In order to preserve the integrity of the detection of infrared radiation
detected by IR detector 18, a cloaking tube 26 may be placed around IR
detector 18 at one end thereof, while the other end of cloaking tube 26
opens near ignition coil 16. Preferably, cloaking tube 26 defines a line
of sight of IR detector 18 directly toward emission coil and element 22.
By limiting the peripheral view of IR detector 18 using cloaking tube 26,
or a similarly functioning structure, IR detector 18 will be limited in
its detection of infrared radiation from a limited number of sources,
which will preferably be ignition coil 16 and combustion and emission
region 20.
The solid materials to receive heating from the combustion of the gaseous
fuel, which solid materials are found within combustion and emission
region 20, must be carefully chosen to withstand extended periods of being
heated within a combustible gas. Preferably, this material is an
aluminum-nickel alloy or a stainless-steel material with an
aluminum-silicon additive such that its melting point is high (e.g. above
1200.degree. F.).
With respect to emission coil 22, it is preferably wrapped around emission
element 24 several times and is spot-welded thereon. Preferably, emission
coil 22 and emission element 24 are both made from KANTHAL.TM., supplied
as 8-gauge rod. This rod is between 4 and 5% aluminum, about 22% chromium,
and substantially comprises iron. The size of the rod is between 0.6
inches and 0.12 inches diameter. While the foregoing represents a
preferred material for emitting infrared radiation from within combustion
and emission region 20, those of skill in the art will understand that
other materials are capable of emitting infrared radiation adequately for
the present inventive system.
While cloaking tube 26 is depicted in FIG. 1A in one embodiment thereof as
a shield or tube to block peripheral vision of IR detector 18, tube 26 may
also be considered to one or more optical transmission fibers capable of
transmitting infrared radiation from either ignition coil 16 or combustion
and emission region 20 so as to communicate the same to IR detector 18. In
such an alternative embodiment, combustion and emission region 20 and
ignition coil 16 may be located at an open gas fuel and air source such as
a gas burner of a stove, where tube 26 transmits infrared radiation by
optical fiber therein from such location at the burner of a stove to a
remote location where IR detector 18 is situated. Such an embodiment of a
gas fired stove provides an environment in which IR detector 18 can be
safely maintained out of the heating zone of the burner. It should also be
understood that IR detector 18 may be further separated from first and
second conductive rods 12, 14 in a gas fired stove embodiment of the
present inventive ignition and combustion control system and method.
Alternatively, a heavy duty IR detector 18 may be maintained closer to the
combustion flames, when properly positioned or thermally shielded by a
mica shield or other transparent shield, so that IR detector 18 may be
positioned directly in between first and second conductive rods 12, 14 and
within the line of sight of solid materials to be monitored for infrared
radiation.
Alternative embodiments oft he inventive ignition and combustion detection
system are seen in FIGS. 1B and 1C. A burner tube 33 is disposed below and
immediately adjacent to ignitor 10. Burner tube 33 has at one end thereof
a gas line 32 feeding a supply of combustible fuel through an orifice 35.
Ambient air, due to pressure differentials, is fed to the inside of burner
tube 33 through a venturi 21 to be mixed with combustible fuel from fuel
inlet 32. Past an opposite end 19 of burner tube 33 is combustion and
emission region 20.
In the embodiment of ignitor 10 seen in FIG. 1B, ignition coil 16 is
positioned outside of and past end 19 of burner tube 33. Thus, ignition of
the supply of combustible fuel emitted from orifice 35 of gas line 32
takes place at end 19 of burner tube 33. Upon combustion, the pressure of
combustible fuel emitted from orifice 35 of fuel end 32 shifts the flame
from the region of ignition coil 16 to combustion and emission region 20.
By such flame shifting, ignition coil 16 is not heated by the flames of
combustion, and emission element 24 within combustion and emission region
20 is heated by the flames of combustion which have shifted away from end
19 of burner tube 33.
As can be seen in FIG. 1B and 1C, emission element 24 is a thin piece of
material which, preferably, has a flat surface effaced toward and within
the line of sight of IR detector 18. Unlike ignitor 10 seen in FIG. 1A,
emission element 24 does not have an emission coil 22 wrapped therearound.
As such, emission element 24 of FIGS. 1B and 1C has a relatively small
thermal mass, which is conducive to rapid emission of infrared radiation
upon heating of the same.
The embodiment of ignitor 10 seen in FIG. 1C shows burner tube 33 having an
ignition hole 17 proximal of end 19. Immediately adjacent to ignition hole
17 and above burner tube 33 is ignition coil 16 of ignitor 10. In this
embodiment, a combustible fuel is fed into fuel inlet 32 and through
orifice 35 so as to, by pressure differential, draw ambient air through
venturi 21 creating a primary fuel-air mixture. The primary mixture of
fuel and air translates to the location of ignition hole 17. Again, by
pressure differential, ambient air is received through ignition hole 17 to
mix with the primary mixture of fuel and air so as to create a secondary
and combustible mixture of fuel and air. As the combustible secondary
mixture of fuel and air begins to surround ignition coil 17 from within
burner tube 33 at ignition hole 17, ignition coil 16 is heated
electrically to a temperature at which the secondary mixture of fuel and
air will combust. Upon combustion, the pressure of gaseous fuel from fuel
inlet 32 will cause the flames of combustion to shift out of burner tube
33 and extend to combustion and emission region 20. By such flame
shifting, ignition coil 16 is outside of the flames of combustion, and
emission element 24 within combustion and emission region 20 is engulfed
within the flames of combustion. Consequently, IR detector 18 essentially
receives infrared radiation solely from combustion and emission region 20
to the exclusion of ignition coil 16 which is no longer electrically
resistance heated.
The concept of shifting the flames of combustion following ignition away
from the hot ignition surface to a solid material exposed to ongoing
combustion may be accomplished through increased gas mixture pressure,
spatial arrangement of the infrared radiators, forced air pressures, or by
other conventional means.
An alternative embodiment from ignitor 10 seen in FIGS. 1A, 1B, and 1C is
an embodiment in which the flames of combustion, subsequent to ignition,
engulf only ignition coil 16. In such an embodiment, ignition coil 16 is
electrically resistance heated to the point of igniting the combustible
gaseous fuel mixture. Subsequent to ignition, ignition coil 16 is no
longer electrically heated, but rather is thermally heated by the flames
of combustion. IR detector 18 thus detects infrared radiation emitted from
ignition coil 16 as it is electrically and then thermally heated. In such
embodiment, the flames of combustion do not heat combustion and emission
region 20. This embodiment is not considered the best mode in that
ignition coil 16 is exposed for prolonged periods to high temperatures due
to the flames of combustion. Additionally, ignition coil 16 has a limited
thermal heat sink in communication therewith so as to transfer heat energy
therefrom to the heat sink. As a result, ignition coil 16 has a shorter
life due to a rigorous environment of constant exposure to high
temperatures, both thermally and electrically. In such embodiment, the
presence of the extended portion of second conductive rod 14 having at an
end thereof emission coil 22 and emission element 24 would not be
necessary. Additionally, the thermal mass of ignition coil 16 should be
increased to lengthen its service life, should the requisite power be
available in the appliance to achieve hot surface ignition temperatures.
The inventive ignition and combustion monitoring device can be placed in a
variety of gas fired appliances such as furnaces, water heaters, barbecue
pits, fire places, stoves, refrigerators, and other appliances where the
ignition and subsequent combustion of a gaseous fuel is required.
The foregoing is a description of preferred embodiments of the inventive
ignition and combustion monitoring device. Components of one such
embodiment are more fully described in Table I, below. The artisan will
understand that different structural, component, and material designs and
arrangements are possible to implement the device seen in FIG. 1A.
FIG. 2 depicts an embodiment of an inventive gas fired furnace containing
the inventive ignitor. A fire box 30 has therein ignitor 10. Ignitor 10 is
supplied with gaseous fuel by a fuel inlet 32. Fuel inlet 32 distributes
the gaseous fuel in a spread out or otherwise extended area. Upon
ignition, a series of combustion plumes 34 heat combustion and emission
region 20 shown in FIG. 2.
The furnace seen in FIG. 2 has an air-intake flow seen by an arrow 36 which
carries a stream of air into fire box 30. A blower fan 35 forces air in
the direction of an arrow 36 into fire box 30. The force of blower fan 35
on the air flow through fire box 30 also forces the heated air within fire
box 30 to exit at an exhaust vent 38. The air of the air stream is heated
within fire box 30 and exits fire box 30 through an exhaust vent 38.
Exhaust vent 38 will preferably exhaust heated air into the ambient where
the furnace is installed so as to heat an intended area.
As seen in FIG. 2, a fuel source 40 deliver fuel gas to a gas valve 42
prior to being delivered to fire box 30. For subsequent combustion, fuel
supply 40 feeds gaseous fuel through a gas valve 42 to fire box 3. Outside
of firebox 30 is a temperature detection and signaling device 44 which
detects ambient temperature within the environment to be heated by the
furnace.
An appliance control board 46 controls the operation of the furnace.
Appliance control board 46 is in electrical communication with a power
supply through power supply leads 48. Control board 46 is in electrical
communication with the temperature detection and signaling device 44
through thermostat leads 52. Appliance control board 46 is also in
electrical communication with blower fan 35 through blower fan leads 42.
Ignitor 10 is in electrical communication, through ignitor and IR detector
leads 56, with appliance control board 46. Appliance control board 46 also
controls a manual gas shut-off valve modulating capability of the furnace
through manual shut-off valve leads 58. Additionally, input and output
communications to appliance control 46 are made to appliance control board
46 through an I/O communications device 60.
An alternative embodiment of the inventive ignitor is shown installed
within a water heating system is seen in FIG. 3. As seen in FIG. 3,
ignitor 10 heats a water tank 62 by combustion plumes 34. As water tank 62
is heated, cold water following in the direction of an arrow 64 causes
water to enter water tank 62, and hot water exits in the direction
indicated by an arrow 66 from water tank 62 upon external demand for same.
The temperature of water within water tank 62 is detected by temperature
and detection signaling device 44 which communicates with control board 46
for the monitoring of the water temperature. A power supply and thermal
limit switch 68 also feeds into control board 46 for the purpose of
detecting excessive water temperatures which, for instance, might tend to
scald a user demanding hot water from water tank 62.
Various operational parameters may be set by a user with a mode-selection
device 70 which is in electrical communication with appliance control
board 46.
As an option to gaseous fuel combustion to heat water tank 62, an
electrical resistance heating system 72 seen in FIG. 3 can also heat the
water within water tank 62. Heating system 72 obviates the need for
ignitor 10 and associated circuitry, except where IR detector 18 and
associated circuitry monitor for structural failure of combustion area
components as discussed above.
In the case of a gas fired hot water heater, the infrared sensor detects
for both low and high radiation being omitted by the second radiator. It
is necessary to so monitor in that forced air is not fed to the combustion
area of the hot water heater. The absence of a forced air stream, in
combination of a poor combustion, may result in the combustion of carbon
and produce a flame from such combustion which emits an excessive amount
of infrared radiation. As such, the method implemented for the inventive
gas fired water heater must anticipate such circumstances and cause the
control of the appliance to respond appropriately.
The burning of carbon is visually indicated by an orange color, and may be
due to an insufficient air supply available to the combustion area of the
gas fired water heater. In the gas fired water heater, a sail switch
function would not be incorporated in that no blower fan is used. Thus,
the method for using the inventive ignition and combustion control system
must anticipate an excessive infrared radiation being detected from the
gas combustion area of the gas fired water heater, the explanation for
which is a poor air supply as opposed to an excessive temperature.
Parameters may be set within the microprocessor and its data storage area
so as to discern between excessive temperatures of the water in the water
heater, and a deprivation of air to the combustion area of the water
heater.
FIG. 3 shows a group of the inventive equipment 74 that is needed for most
gas fired appliances to operate with the inventive ignition and combustion
control system and method.
B. The Presently Preferred Electronic Controller: FIGS. 4 through 5D.
Appliance control board 46, seen in FIGS. 2-3, incorporates a variety of
both hardware and software to accomplish the function of operating a gas
fired appliance. In FIG. 4, a microprocessor 92 may have an optional
non-volatile memory, such as an EPROM, to store additional software and
data to be fed to appliance control board 46, seen in FIGS. 2-3. An
external communications module 78 can be used to feed appliance data to
peripheral equipment, as well as to receive data to be fed to the
appliance. A gas modulator circuit 80 is used to control the flow of gas
going through a valve to the appliance. An LED indicator for alarms is
seen at 82. Device 82 may include visual LED indicators, sound alarms, or
a combination thereof.
The controlling of blower fan 35, seen in FIG. 2, may be controlled by a
blower fan control module 84 seen in FIG. 4. Power supply and voltage
regulation is accomplished by a module seen at 88. The temperature that is
achieved by the medium being heated may be controlled by a temperature
input 90 which directly measures the medium being heated and communicates
a signal with microprocessor 92.
All of the foregoing data is communicated with microprocessor 92, seen in
FIG. 4, for being processed. Microprocessor 92 has an analog to digital
converter 94 which converts the signals from the aforedescribed devices in
preparation for processing the data contained in the signals.
In the presently preferred embodiment, microprocessor 92 in FIG. 4, and IC1
seen in FIG. 5, is an example of a digital processor means. Such a digital
processor means can be a general purpose microprocessor or an equivalent
device. Alternatively, it may be desirable to utilize a more powerful
microcomputer, such as an IBM personal computer, to devise a
microprocessor-based apparatus specifically designed to carry out the data
processing functions incidental to this invention. Importantly, the
hardware which embodies the processor of the present invention must
function to perform the operations essential to the invention and any
device capable of performing the necessary operations should be considered
an equivalent of the processor means. As will be appreciated, advances in
the art of modem electronic devices may allow the processor to carry out
internally many of the functions carried out by hardware illustrated in
FIGS. 2 though 5 as being independent of the processor. The practical
considerations of cost and performance of the system will generally
determine the delegation of functions between the processor and the
remaining dedicated hardware. However, a low cost processor is desirable.
Visual display aspects of I/O device 60 seen in FIGS. 2 and 3, and
controlled through LED indicator 82 of FIG. 4, performs the function of a
display means. As intended herein, the display means may be any device
which enables the operating personnel to observe visually displayed or
audibly reported operational parameters calculated by the microprocessor.
Thus, the display means may be a device such as a cathode ray tube, an LCD
display, a chart recorder, and/or speaker, or any other device performing
a similar function. In the preferred mode, the display means may be one or
more series of low cost LEDs.
The functional block diagram of FIG. 4 can be implemented by the circuitry
depicted in FIGS. 5A-5D, the components thereof being more fully described
in Table II, below. The artisan will understand that different circuit
designs are possible to implement the functional block diagram of FIG. 4.
Thus, FIGS. 5A-5D and the component list of Table II are offered only for
purposes of illustration and not for purpose of limitation of the
inventive method and system.
IV. The Method
Attention is next turned to a detailed description of the presently
preferred method by which the system of the present invention is used to
ignite and monitor the combustion of a fuel gas, and to control the
operation of a gas fired furnace, with particular reference to FIGS. 6
through 14, 15-A through 15H, and 16 through 19 which illustrate one
presently preferred embodiment of the instructions which may be utilized
for digital processor control of the gas fired furnace depicted in various
aspects in FIGS. 1-2, and 4-5.
Both the function block diagram of FIG. 4 and the electrical schematic of
FIGS. 5A-5D illustrate a presently preferred embodiment of an inventive
gas fired appliance ignition and combustion monitoring system.
As will be appreciated by those of ordinary skill in the art, and as noted
above, while the system and method as described in reference to the
preferred embodiments herein illustrate the system and method as
implemented using state of the art digital processing design and
corresponding program instructions for controlling the processor, the
system and method could also be implemented and carried out using a
hardware design which accomplishes the necessary electronic processing,
which is thus intended to be embraced within the scope of various of the
claims as set forth hereinafter.
The method of the present invention is seen in overview in FIGS. 6 and 7
which depict flow charts schematically illustrating the primary routines
of one presently preferred method for programming both the initialization
mode and the operational mode, which modes are performed essentially by
the digital processor means of the fuel gas ignition and combustion
monitoring system in accordance with the method of the present invention.
As seen in FIGS. 6 and 7, the software programming is essentially divided
into two sections: respectively, the initialization loop and the main
execution loop. The initialization loop, as seen in FIG. 6, prepares the
system hardware for the main execution loop and in part verifies
functionality of the hardware. The main execution loop, as seen in FIG. 7,
controls all other functions in the operation of the furnace.
Microprocessor control of the preferred embodiment of the inventive furnace
is detailed in Appendix A hereof by a software source code listing of
programs, subprograms, and subroutines, each of which includes
documentation descriptive thereof. Each of the programs, subprograms, and
subroutines in Appendix A is labeled with a title seen in the top-most
labeled step corresponding to a title of a software flow chart seen in
FIGS. 6 through 14, 15-A-15H, and 16-19. Each of the FIGS. 6-14, 15-A-5H,
and 16-19 graphically sets forth a series of steps for performing a
program, subprogram, or subroutine for which a listing appears in Appendix
A. A description of each of these steps in the Figures is found in
Appendix B, which with the source code listings in Appendix A provides a
complete understanding of the method of a preferred embodiment of the
invention. A summary of the general functions performed by the flow charts
depicted in each of the Figures, however, is set forth below.
FIG. 6 depicts steps to prepare the microprocessor for the ongoing
execution of the software by initializing the data storage addresses and
registers, as well as assignment of addresses for subsequent storage of
data. Miscellaneous maintenance and initialization routines are carded
out.
The steps depicted in FIG. 7 will now be generally described. At the start
of the steps, the blower fan motor is initiated into directing an air
stream into the furnace combustion chamber. The ignitor receives a current
developing a voltage potential between the two electrically conductive
rods so as to resistance heat a first radiator extending there between.
The voltage applied to the first radiator is monitored by the
microprocessor.
Infrared radiation is detected as it is emitted by the resistance heated
first radiator, and particularly as the stream of air from the blower fan
engulfs and cools the first radiator so as to reduce the infrared
radiation emitted therefrom. A verification routine, similar to the sail
switch function described above, acknowledges that the blower fan is
operating properly, or alternatively that a malfunction has occurred. A
gas valve is opened, under the control of the microprocessor, as the
blower fan increases its air flow into the combustion chamber. The first
radiator is heated for a period of two seconds, which is the desired
amount of time to cause a hot surface ignition of the combustible gas
mixture that is entering the combustion chamber. Another period of four
seconds passes during which flames from the now ignited combustible gas
heat the second radiator which is situated at the end of the longer of the
two rods on the ignitor.
After a six second period has passed, infrared radiation is detected by the
infrared sensor, where the infrared radiation is radiating from the second
radiator. In the event that infrared radiation is insufficient, the
microprocessor is signaled that an ignition has failed. In such case, the
supply of gas to the combustion chamber will be shut off, and the blower
fan will cause a purge of the combustion chamber for a period of 45
seconds.
The foregoing routine of blower fan operation, resistance heating of the
first radiator, and attempt to detect infrared radiation coming from the
second radiator will continue for a total of three cycles as the system
repeats attempts to ignite the combustible fuel. Once combustion within a
six second period is verified by IR detection from the second radiator,
then a period of 45-50 seconds passes during which a proper infrared
radiation level must be detected by the infrared sensor, or else the
system will shut down the gas flow to the combustion chamber and will
begin the foregoing retry attempts to ignite the combustible fuel.
Once ongoing combustion is established by sufficient detection of radiation
by the infrared sensor, the thermostat is monitored to determine if a
request for heat has been signaled. In the event that the thermostat is
not requesting to heat, then the flow of gas to the combustion chamber
will cease, combustion will cease, and the fire pot of the furnace will be
purged by the blower fan for a period of 45 to 50 seconds.
In the event that the furnace becomes too hot, then an ECO switch in
communication with the furnace will send a signal to the microprocessor to
shut the power down to most of the system. Particularly, the gas valve is
no longer electrically modulated and the flow of gas to the combustion
chamber ceases. Upon such cessation of flow of gas to the combustion
chamber, combustion also ceases. Upon such a thermal failure, a period of
two and one-half minutes passes during which electrical power to the gas
valve is monitored to determine if a cooling of the furnace has occurred
which is signified by power being applied to the gas valve. In the event
that a cooling has transpired, then the ignition routine described above
will take place.
FIG. 7 shows at step 17 a routine titled "IGNITION". This routine includes
most basic operations of the inventive ignition and combustion control
system for the method of controlling the gas fired furnace. This routine
is further expanded in FIGS. 15a-15h. FIGS. 15a-15h reveal that step 17
seen in FIGS. 7 calls for a variety of other routines for the purpose of
accomplishing the basic functions of the ignition and combustion and
control method for the gas fired furnace.
The remains of FIGS. 8 through 19 will now be briefly discussed in
perspective to the overall operation of the furnace.
The flow chart seen in FIG. 8 essentially monitors infrared radiation
detected by the infrared sensor by reading the voltage therefrom.
In FIG. 9, a maintenance routine performs a series of steps necessary for
the modulation of a valve controlling the flow of fuel gas to the furnace
combustion area.
In FIG. 10, a routine performs a series of steps necessary for controlling
the blower fan to the furnace.
In FIG. 11, high and low speeds of the blower fan are controlled given a
variety of operation conditions.
In FIG. 12, verification of the presence of the flame is determined as well
as a utility performed for determining if the furnace is overheating.
FIG. 13 monitors the overall system to determine if a malfunction has
occurred and will initiate visual alarms in the event of an operational
malfunction.
FIG. 14 shows steps to perform the sail switch function, as described
above, in which a decrease in infrared radiation is detected from the
first radiator as a flow of air engulfs the first radiator during the
electrical resistance heating thereof to determine that an adequate flow
of air is entering the furnace combustion chamber. Appropriate flags are
set in the event that insufficient air supply is reaching the combustion
chamber as determined by the detection of infrared radiation and
predetermined standards for proper infrared radiation in application
specific circumstances.
FIGS. 15A-15H graphically depict steps performed by the inventive method
controlling most basic functions of the furnace. Particularly, monitoring
of infrared radiation between predetermined low and high levels form the
basic routine enacted by the depicted program steps titled "IGNITION".
In FIG. 16, a routine is graphically depicted for reading the voltage
applied to the first radiator, which is the ignition coil for igniting the
combustible gas in the combustion chamber of the furnace. By monitoring
the voltage applied to the ignition coil, it may be determined whether the
ignition coil is inoperable due to structural failure, or whether it is
being heated properly to a temperature necessary for hot surface ignition
of the combustible fuel in the combustion area of the furnace.
FIG. 17 graphically depicts a routine for reading the voltage applied to
the motor of the blower fan so as to monitor the operation thereof.
FIG. 18 is a routine for modulation of the voltage of the ignition coil to
determine and to verify, in addition to other routines set forth
elsewhere, whether the ignition coil is of sufficient temperature for hot
surface ignition of the combustible fuel.
FIG. 19 is a routine for modulating the infrared level detected by the
infrared sensor, and for regulating the voltage applied to the ignition
coil, while also comparing the detected infrared radiation from the first
radiator to a predetermined standard for such radiation maintained in a
data memory storage area associated with the microprocessor.
The figures depicting flowcharts may be further understood by referencing
their calling routines, by the source code routines of like-title in
Appendix A, by the flow chart step descriptions in Appendix B, or by the
general descriptions for the system and method of the present invention
set forth herein.
It will be appreciated that the microprocessor 92 of FIG. 4, or the digital
processor IC1 of FIG. 5 which is identified as a 16C71 microprocessor,
could be programmed so as to implement the above-described method using
any one of a variety of different programming languages and programming
techniques.
The method of the present invention is carried out under the control of a
program resident in the 16C71 microcomputer and associated circuitry.
Those skilled in the art, using the information given herein, will readily
be able to assemble the necessary hardware, either by purchasing it
off-the-shelf or by fabricating it and properly programming the
microprocessor in either a low level or a high level programming language.
While it is desirable to utilize clock rates that are as high as possible,
and as many bits as possible in the incorporated A/D converters, the
application of the embodiment and economic considerations will allow one
skilled in the art to choose appropriate hardware for interfacing the
microprocessor with the remainder of the embodiment. Also, it should be
understood that for reasons of simplifying the diagrams, power supply
connections, as well as other necessary structures, are not explicitly
shown in the figures, but are provided in actuality using conventional
techniques and apparatus.
TABLE I
______________________________________
IGNITOR PARTS LIST
______________________________________
DESCRIPTION DEVICE QUANTITY
______________________________________
SHOULDER KEYSTONE PART 1
WASHER
SPACER KEYSTONE PART 1
LOCK RING AU-VE-CO PART 1
METAL BRACKET 1
MICA INSULATOR
KEYSTONE PART 1
SPADE LUG SMALL
KEYSTONE PART 1
SPADE LUG KEYSTONE PART 2
CIRCUIT BOARD 1
PIN DIODE IR SHARP PD410P1 1
NUT 6-32 4
KANTHAL ROD GA.127 2
KANTHAL WIRE GA.0142 2
LOCK WASHER ARDEN FASTENER 2
______________________________________
TABLE II
______________________________________
FURNACE CONTROLLER PARTS LIST
DESCRIPTION DEVICE QUANTITY
______________________________________
POWER MOSFET 1RFZ40 1
POWER DIODE MUR1520 1
VOLTAGE 7805CT 1
REGULATOR +5
DARLINGTON TIP117 2
TRANSISTOR
P-MOSFET IRF9Z30 1
N-MOSFET IRF530 1
FET IRF020 1
HIGH SIDE MIC5014 1
DRIVER
N-FET 2N7000 2
N-TRANSISTOR 2N4401 6
P-TRANSISTOR 2N4403 1
MICROPROCESSOR PIC16C71 1
CAPACITOR 330 uF 25 V 3
LOW IMPEDANCE
CAPACITOR 10 uF 50 V 1
CAPACITOR 1 uF 50 V 3
CAPACITOR .1 uF 6
RESONATOR KBR4.00MKST 1
DIODE 1N4002 12
ZENER DIODE IN5226 1
RESISTOR 10M OHM 1
RESISTOR 200K OHM 2
RESISTOR 100K OHM 1
RESISTOR 91K OHM 1
RESISTOR 51K OHM 2
RESISTOR 10K OHM 19
RESISTOR 5.1K OHM 3
RESISTOR 2K OHM 1
RESISTOR 1K OHM 1
RESISTOR 510 OHM 1
LED MAA3368S 1
MINI-FIT 39-29-1188 1
CONNECTOR
MINI-FIT 39-01-2180 1
CONNECTOR
MINI-FIT 39-00-0060 18
CONNECTOR PINS
CIRCUIT BOARD 1
STAND OFF 4
CONFORMAL 1
COATING
ALUMINUM 1
BRACKET
BOLT #4-40 F581M 4
NUT #4-40 F557M 3
MICA-INSULATOR 242-4672 3
SHOULDER 3
WASHER
______________________________________
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